rootslab / cocker

Cocker, a socket module to aggressively handle connection retries.

Cocker

Cocker, a socket module to aggressively handle connection retries.

NOTE: It directly inherits from net.Socket.

Table of Contents

• Install
• Run Tests
• Constructor
• Options
• Properties
• Methods
  • bye
  • run
  • die
  • hunt
  • prey
  • watch
• Events
• Examples
  • Simple Mode
    • re-connection loop with run
  • Native Promises
    • connection with hunt
    • connection with prey (through an address list)
    • looping with watch
    • looping (indefinitely) with hunt and watch
• MIT License

---

Install

$ npm install cocker [-g]

require:

const Cocker  = require( 'cocker' );

Run Tests

$ cd cocker/
$ npm test

to execute a single test file simply do:

 $ node test/file-name.js

---

Constructor

Arguments between [ ] are optional.

Cocker( [ Object options ] )

or

new Cocker( [ Object options ] )

Options

NOTE: default options are listed.

It accepts a configuration hash/object:

option

{
 , address : Object
 , connection : Object
 , reconnection : Object
}

option.address (default)

{
    host : '127.0.0.1'
    , port : 0
    , family : null
    /*
     * Specify an IPC endpoint, like a unix domain socket, if a string is
     * provided, the TCP-specific options above are ignored.
     * For further details, see "Identifying paths for IPC connections" in 
     * the /api/net section.
     */
    , path : null
 }

option.address (additional options for net.Socket)

{   
    // should connect from
    localAddress : undefined
    , localPort: undefined
    // custom lookup and hints
    , lookup : dns.lookup 
    , hints : 0
 }

option.connection

 {
    encoding : null
    , keepAlive : true
    , timeout : 0
    , noDelay : true
    , allowHalfOpen : false
 }

option.reconnection

 {
    trials : 3
    , interval : 1000
    /*
     * A value to use for calculating the pause between two
     * connection attempts. Default value is the golden ratio.
     * Final value is calculated as:
     * interval * Math.pow( factor, curr.attempts + 1 )
     */
    , factor : ( Math.sqrt( 5 ) + 1 ) / 2
 }

---

Properties

NOTE: do not mess up with these properties.

a property that holds the current configuration object

Cocker.options : Object

current number of connection attempts

Cocker.attempts : Number

a flag to signal the current status of the connection

Cocker.lost : Boolean

a flag used to disable reconnection (after #hunt Promise resolution)

Cocker.stop : Boolean

current lapse of time (to wait) until the next connection attempt

Cocker.lapse : Number

---

Methods

all the methods from net.Socket module are inherited.

name	description
bye	end the connection.
run	connect to a socket or attempting to.
die	end the connection. (Promise)
hunt	connect to a socket or attempting to. (Promise)
prey	connect using a list of hosts. (Promise)
watch	re-connect after losing the current connection. (Promise)

Arguments between [ ] are optional.

Cocker.bye

end the connection (without re-connecting).

'bye' : function ( [ Buffer | String data [, String enc ] ] ) : undefined

Cocker.run

connect to a socket or attempting to (k times).

// it optionally accepts a cocker option object to reconfigure the socket.
'run' : function ( [ Object cocker_options ] ) : undefined

Cocker.die

end the connection (without re-connecting).

// Promise will not be resolved until 'lost' event
'die' : function ( [ Buffer | String data [, String enc ] ] ) : Promise

Cocker.hunt

connect to a socket or attempting to (k times).

/*
 * Try to connect to a socket. Promise will not be resolved until 'online',
 * rejected after 'lost' event; it optionally accepts a cocker option object
 * to reconfigure the socket.
 */
'hunt' : function ( [ Object cocker_options ] ) : Promise

Cocker.prey

try to connect until success, using a list of optional hosts/config.

/*
 * It recursively scan a list, using #hunt Promises. The #prey Promise will 
 * not be resolved until a connection will be made, definitively rejected
 * when no hosts had accepted one. 
 * Every host in the list should be an object like Cocker.options.address.
 */
'prey' : function ( Array hosts ) : Promise

Cocker.watch

try to re-connect after losing the current connection.

/*
 * When the current established connection is lost, it tries to reconnect.
 * This Promise has the same resolution as for #hunt, the only difference is
 * that this Promise was "registered" on socket disconnection, then it will be
 * resolved/rejected only after capturing a 'lost' event from the current
 * broken connection. See examples.
 */
'watch' : function ( [ Object cocker_options ] ) : Promise

---

Events

all the events from net.Socket module are inherited.

!online: connection was established.

// when: soon after socket !connect event
'online' : function ( Object address  )

!offline: connection is down.

// when: on the first !close event for the current socket
'offline' : function ( Object address  )

!attempt: current connection attempt.

// when: after !offline, on every connection attempt, until !lost or !online 
'attempt' : function ( Number t, Object address, Number lapse )

!lost: no other attempts will be made, connection is definitively lost.

// when: soon before the last !close event.
'lost' : function ( Number t, Object address, Number lapse )

---

Examples

Simple Mode

• re-connection loop with run

Native Promises

• connection with hunt
• connection with prey (through an address list)
• looping with watch
• looping (indefinitely) with hunt and watch

See examples.

MIT License

Copyright (c) 2013-present < Guglielmo Ferri : [e-mail] >

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.